Changing look: from Compton-thick to Compton-thin, or the rebirth of fossil active galactic nuclei
Changing look: from Compton-thick to Compton-thin, or the rebirth of fossil active galactic nuclei
We discuss the properties of a small sample of type 2 Seyfert galaxies whose X-ray spectra changed appearance on time-scales of years, becoming reflection-dominated from Compton-thin, or vice versa. A reflection-dominated spectrum is usually taken as evidence of Compton-thick absorption, but we instead argue that such a spectrum is due …